I. Field
The present disclosure relates generally to communication, and more specifically to techniques for combating interference in a wireless communication system.
II. Background
A wireless multiple-access system can support communication for multiple terminals on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Multiple terminals may simultaneously transmit data on the reverse link and/or receive data on the forward link. This may be achieved by multiplexing the transmissions on each link to be orthogonal to one another in time, frequency, and/or code domain. The orthogonality ensures that the transmission for each terminal minimally interfere with the transmissions for other terminals.
A wireless communication system may have many sectors, where the term “sector” can refer to a base station and/or its coverage area depending on the context in which the term is used. On the reverse link, the transmissions from terminals in the same sector may be orthogonally multiplexed to avoid interfering with one another. However, the transmissions from terminals in different sectors may not be orthogonal, in which case each terminal may cause interference to terminals in other sectors. The inter-sector interference may significantly degrade performance for disadvantaged terminals observing high levels of interference.
To combat inter-sector interference, a wireless communication system may employ a frequency reuse scheme whereby not all frequency channels available in the system are used in each sector. For example, a system may employ a 7-sector reuse pattern and a frequency reuse factor of 7. In this system, the overall system bandwidth may be divided into seven non-overlapping frequency channels, and each sector in a 7-sector cluster may be assigned one of the seven frequency channels. Each sector uses only one frequency channel, and every seventh sector reuses the same frequency channel. With this frequency reuse scheme, each frequency channel is only reused in sectors that are not adjacent to each other, and the inter-sector interference observed in each sector is reduced relative to the case in which all sectors use the same frequency channel. However, a large frequency reuse factor (e.g., two or more) represents inefficient use of the available system resources since each sector is able to use only a fraction of the overall system bandwidth.
There is therefore a need in the art for techniques to combat interference in a more efficient manner.